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6.5 mm Grendel
to |origin= |type= Rifle |designer= Bill Alexander |design_date= 2003 http://www.alexanderarms.com/grendel.htm |parent=PPC |case_type=Rimless, bottleneck |is_SI_specs=yes |bullet= 6.5 |neck=7.44 |shoulder=10.87 |base=11.15 |rim_dia=11.2 |rim_thick=1.5 |case_length=38.7 |length=57.5 |rifling=1 in 8" or 1 in 9" |primer= Small rifle |velocity= |energy=1900 |bw1=90 |btype1=Speer TNT |vel1=2880 |en1=1658 |bw2=120 |btype2=Norma FMJBT |vel2=2700 |en2=1942 |bw3=123 |btype3=Sierra Matchking |vel3=2650 |en3=1917 |bw4= 130 |btype4= Norma |vel4=2510 |en4=1818 |bw5= 108 |btype5= Scenar (moly) |vel5=2790 |en5=1866 |test_barrel_length= 24 inches |balsrc=Alexander Arms Pressure-safe Load Data }} The 6.5 mm Grendel (or 6.5x39mm Grendel) is a 6.5 mm caliber intermediate cartridge developed in 2002 by Bill Alexander of Alexander Arms and Arne Brennan of Competition Shooting Sports. This cartridge is an evolution of Dr. Lou Palmisano's PPC case which has dominated competition shooting for over 20 years.6PPC -- The Benchmark of Accuracy The 6.5 Grendel was designed as a low recoil, high accuracy, long-range cartridge for the AR-15 platform. Development and history , 6.5 Grendel, 5.56 mm NATO|thumb|112px|right]] The Grendel design philosophy was "start slow and end fast". High muzzle velocities accelerate barrel wear and increase the percentage of recoil due to escaping gases but only yield good impact energy if the bullet is efficient at carrying its velocity downrange. Constrained by the length of the 5.56 mm NATO round, but wanting to launch a much heavier bullet, the Grendel designers hit on a short, fat case for more powder volume while saving space for long, streamlined, high ballistic coefficient (BC) bullets that give up little of their energy in-flight. Firing factory bullets from 90 to 129 grains , its muzzle velocity ranges from with 129- and bullets to with bullets (similar in velocity to a 5.56 mm round). Timeline *1998: Arne Brennan investigates .22 PPC, 6 PPC in search of a more capable competition and hunting round. *2000: Arne Brennan begins shooting a 6.5 PPC wildcat cartridge from his custom AR-15 platform. *2001: Arne Brennan and Bill Alexander introduced to each other by Lothar Walther. *Mar 2002: First production 6.5 Grendel brass cartridges manufactured to specification by Lapua. *May 2003: First prototype 6.5 Grendel weapon demonstrated at Blackwater Shoot-out. *May 2006: Independent ballistic gelatin testing completed for TNT, Norma, SMK, and SMK prototype. *Aug 2006: Bill Alexander publishes pressure safe load table for AR platforms with 14.5- to 28.0-inch (370–710 mm) barrels. *Feb 2007: Production Wolf brand ammunition becomes available. Performance Proponents assert that the Grendel is an ideal middle ground between the 5.56 mm NATO and the 7.62 mm NATO, taking the best attributes of each. It has a flatter trajectory and retains greater terminal energy at extended ranges than either of these cartridges due to its higher ballistic coefficient.Grendel ballistics table Production rifles have consistently achieved sub–minute of arc (MOA) groups at test ranges out past 600 meters.Four shooters achieve group average at On March 6, 2006, Arne Brennan achieved a witnessed group at .660 yard Sub MOA Group Similar accuracy was demonstrated at recent Blackwater Shootouts.Armed Forces Journal Competitions have begun to be won with the 6.5 Grendel although use of the round is still not common in competition.Robert Whitley NRA win 5 Mar 05IHMSA (silhouette pistol) Big Bore Unlimited Champion 20053rd Place behind .308 AR10s - ahead of all .223s (second to last article) External ballistics As noted above, the Grendel case is very closely related to the PPC case. When sufficient load data was made available, a thorough study of the Grendel case, which constitutes a precisely dimensioned combustion chamber when the round is chambered, was done with the following results. In general, each additional grain of bullet weight will reduce muzzle velocity by 10 ft/s (3 m/s) and each additional inch of barrel length will increase muzzle velocity by 20 ft/s (6 m/s). Therefore, a handy rule of thumb is "one inch of barrel length equals two grains of bullet weight (1 mm → 5 mg)". Specific details are available as graphs derived from Alexander Arms' public domain load table linked below. Terminal ballistics Alexander Arms contracted Speer Law Enforcement to perform terminal ballistics tests in accordance with standard F.B.I. Protocols and their standard in-house procedures. They use blocks of ten percent ballistic gelatin, calibrated with a BB. These results were made public in May of 2006. All tests were completed using either 14.5- or 16.0-inch (370 or 400 mm) chrome-lined Alexander Arms Tactical rifles and shot from either 50 or 100 yards to simulate combat conditions using short-barreled M4 format weapons. Barrel pressures were less than 345 MPa (50,000 psi). These are all production rifles and ammunition except for the prototype Sierra MatchKing (now a production bullet). In addition to the photos shown below, a TNT was tested resulting in explosive fragmentation after penetrating only 0.5 in (13 mm). The Sierra MatchKing penetrated before yawing and fragmenting. The Alexander Arms Tactical 16 carbine ( barrel) was used at a range of . Impact velocity: . Maximum penetration of the SMK was , maximum permanent cavity diameter was more than with lesions running to gel block exterior surfaces. Depth to the maximum permanent cavity was . The bullet fragmented, with seven large pieces visible within the block. Jacket sections came to rest at 11.75 and 16.25 inches (298 mm and 413 mm), and the bullet core at . The prototype SMK penetrated before yawing and fragmenting. The Alexander Arms Tactical 14.5 carbine ( barrel) was used at a range of . Impact velocity was . The 123 SMK penetrated to a depth of , maximum permanent cavity diameter was more than with lesions running to block exterior surfaces. Depth to the maximum permanent cavity was . The bullet fragmented into multiple small fragments with jacket pieces visible at 11 and 13 inches (280 and 330 mm). A small core fragment was visible at a maximum depth of . The Norma FMJ penetrated before veering out the side of the block and impacting the support frame. No fragmentation was evident, but the slug is believed to have tumbled at about with its maximum permanent cavity at . Lesions of more than were torn through the top and bottom block surfaces. The bullet was fired from an Alexander Arms Tactical AR-15 rifle at a range of with a chronographed impact velocity of . Notes Periodical References (with no online copy) *A. Guns 'n' Ammo: Book of the AR-15, 2004, "The 6.5mm Grendel," David Fortier, p. 66. *B. Special Weapons for Military & Police, Annual #27 2004, "Beyond the 5.56mm NATO," Stan Crist, p. 62-67. *C. Guns 'n' Ammo: Book of the AR-15, 2005, "6.5 Grendel and 6.8 SPC," David Fortier, p. 32-44. *D. Shooting Times, February 2005, "Cooking up Loads for the 6.5 mm Grendel," David Fortier, p. 52-56. *E. Shooting Illustrated, September 2005, "6.5 mm Grendel and Alexander Arms," J. Guthrie, p. 34-37, 67-69. *F. Petersen's: Rifle Shooter, March/April 2006, "Cartridge Efficiency - Why case shape matters," M.L. McPherson, p. 22-24. *G. Shooting Times, January 2007, "Other AR Chamberings," Sidebar Article, David Fortier, p. 56. *H. Special Weapons, Semi-Annual #50 2007, "The Super Versatile AR," Charlie Cutshaw, p. 44-45, 80-83. *I. Special Weapons, Semi-Annual #50 2007, "5.56mm NATO Alternatives," Stan Crist, p. 52-59. *J. Shooting Times, March 2007, "Les Baer's 6.5mm Grendel AR Sets a New Standard," David Fortier, p. 26-32. *K. Special Weapons for Military & Police #52, Spring 2007, "BETTER-IDEA 6.5mm GRENDEL," Stan Crist *L. Special Weapons for Military & Police #52, Spring 2007, "New Battlefield Requirements - New Rifles and Ammo Needed," Charlie Cutshaw See also *6.8 mm Remington SPC *List of firearms *List of handgun cartridges *List of rifle cartridges *List of individual weapons of the U.S. Armed Forces External links * Alexander Arms website * 6.5 Grendel Enthusiast Website * Stanley C. Crist, "Small Arms Ammunition for the 21st Century: Hight-Performance Alternatives to the 5.56 NATO Round" (pdf), Infantry magazine, May-June 2006 * J. Guthrie, "6.5mm Grendel & Alexander Arms", Guns and Hunting, National Rifle Association, accessed November 28, 2006 * Jeff Quinn, "Sabre Defence & Alexander Arms New M-4 Style 6.5mm Grendel AR Rifles", Gunblast.com (online magazine), April 20, 2006, accessed November 28, 2006 * David M. Fortier, "A New Cartridge for the AR: The 6.5mm Grendel from Alexander Arms" (pdf), Small Arms Review magazine, vol 8, no. 6, March 2005, p. 25-27 * 6.5 Grendel Cartridge Guide at 6mmBR.com * Defense Review on the 6.5 Grendel * Major Rob Berg, Sharper Shooting: Upgrading Ammunition Lethality, Military.com (online magazine), January 2005 * 6.5 Grendel Ballistics Comparison to 5.56mm, 6.8 SPC, and 7.62 NATO * 6.5 Grendel Muzzle Velocity Change with Barrel Length *Reference AA Load Data Below * 6.5 Grendel Muzzle Velocity Change with Bullet Weight*Reference AA Load Data Below * Alexander Arms Pressure-safe Load Data * Basic Ballistics by Anthony G Williams * Comprehensive Wound Ballistic Simulation * 6.5 Grendel - Origins and Performance by Arne Brennan * 6.5 Grendel Bolt Action Capability * Robert Whitley, 6mmAR Wildcat based on the 6.5 Grendel * Henning Wallgren and Tom Pfeiffer, The Long Range AR - The 6.5 Grendel * David Fortier, Evolution of an AR - A look at where the M16/AR-15 platform is headed, Guns & Ammo magazine, March 2005 * New Rifle and Ammo for the 6.5 Grendel by Les Baer * Scott Medesha, So You Want To Make Your Mouse Space Gun Roar!, online article, accessed December 8, 2006. * 6.5 Grendel vs. 6.8 SPC, revisited, Airborne Combat Engineer, online magazine, April 7, 2006. * Lapua Load Data for 6.5 Grendel, .pdf file p.7/book p. 18, 18.75" barrel * David M. Fortier, "Piston-Powered ARs - Three Ways!" (pdf), Shotgun News magazine, July 2006 * Contender and Encore Pistol Barrels in 6.5 Grendel * Accurate 2230 reloading data Category:Pistol and rifle cartridges de:6,5 mm Grendel